A Big, Beautiful Number

The maximum amount of supported RAM you can pile onto a Windows server is now 1 Terabyte. That's TB, an abbreviation you might want to
get used to.

Microsoft quietly updated its
supported memory limits to 1TB
with the release of Windows Server 2003 Service Pack 1 and the launch of Windows Server 2003 x64 editions. Officially, four operating
systems support the new cap: the Enterprise and Datacenter editions
of Windows Server 2003 with SP1
for Itanium-based Systems and of
Windows Server 2003 x64.

Not a lot of server applications require 1TB of RAM right now.
The most obvious use is for high-end benchmark runs. Microsoft and Hewlett-Packard currently outfit
their joint HP Integrity Superdome servers with 1TB of RAM (along with 64 Itanium 2 processors and 2,700 36GB SCSI disks) for a run at the Transaction Processing Council's carefully watched TPC-C benchmark.

Whatever result the companies get will be key to industry perceptions
of the scalability of Microsoft's
forthcoming SQL Server 2005.
Anyone with a little math
background, and that's almost
everyone in the computer industry, will notice that the 1TB RAM
limit doesn't begin to approach the
theoretical maximum of 64-bit
systems, which is somewhere in
the neighborhood of 16TB.

The 1TB limit has to do with a Microsoft RAM support policy,
which is to support only as much memory as it can test, according
to John Borozan, a senior product
manager in the Windows Server
business group. "That's the largest system that's available to us today," Borozan said. For the record, to
arrive at Windows XP Professional x64 Edition's 128GB RAM limit, Microsoft tested the client OS on
a server with 128GB of memory.

RAM Tough
It will be a while before most
organizations can afford to put
anywhere near a Terabyte of RAM into a server. HP ran the TPC-C benchmark on a Superdome system running HP-UX and an Oracle database that became available in April 2004. At the time, the memory accounted for $5 million of the system's overall price tag
of about $8 million.

Memory prices do fall, but not
that fast. For most organizations,
the benefits of 64-bit systems will occur closer to earth, where the AMD64 and Intel EM64T chips
and new Windows OS provide a
way to break through the 32-bit
memory barrier of 4GB without resorting to convoluted memory
management tricks. The boost in RAM means applications have to
go to disk less often, improving
performance for numerous
applications, including large
databases and other line-of-
business applications. Windows
Terminal Services and Citrix
applications are also likely to see
a big performance boost.